Cement-roasting apparatus



April 27 1926.

l. E. LANHOFFER CEMENT ROASTING APPARATUS Filed May 24, 1922 4 Sheets-Sheet 1 w Inye72n= 31m 2.

April 27 1926.

l. E. LAN HOFFER CEMENT ROASTING APPARATUS Filed May 24, 1922 4 Sheets-Sheet 2 In venfafi April 27,1926.

|. E. LANHOFF'ER CEMENT ROASTING APPARATUS Filed Ma y,24, 1922 4 Sheets-5heet s April 27 1926. 1,582,831

'1. E. LANHOFFER CEMENT ROASTING APPARATUS Filed May 24. 1922 4 Sheets-$heet 4 lizz enl mwtype.

Patented Apr. 27, 1926.

UNITED STATES' PATENT OFFICE.

IVAN EMILE LANHOFFER, OF PARIS,

cnunmr-nonsrme urannrus Application filed Kay 24, 1922. Serial No. 563,451.

The rincipal object of the invention is to provide an apparatus suitable for carrying out a, process in which a low-temperature treatment of 'the raw material is immediately' followed by a .high temperature treatment in a separate furnace, such a process forming the subject of a separate United States patent application Serial No. 563,452, filed May 24, 1922 of even date herewith.

Rotaryfurnaces heretofore employed for the roasting or calcining of cement have been found to be ineflicient as compared with some types of vertical furnace. In spite of all attempts at heat insulation, there has been considerable loss due to radiation owing to the extensive surface areas of these furnaces. Also, in these furnaces, the material is not in such intimate contact with the flame as in the vertical furnaces but maybe said to be only indirectly heated as the heating is accomplished partly through the medium of the hot gases and partly through the medium of the heated walls of the furnace.

A further object of the invention is 'to :ombine with a sectional rotary furnace fitted with heat control means, a heat recovery ap paratus and'means for dividing the stream of hot gases issuing from the high temperature treatment so that a desired proportion can be treated for heat recovery and the remainder may be admitted to the low temperature treatment furnace. Another object is to provide control means for dealing with the gases after heat recovery treatment so that any desired proportion of such treated gases may be admitted to the low temperature treatment.

As will appear, other objects consist in providing means for rendering the heat recovery as eflicient and controllable as possible, in roviding means for attaining the best possible heat utilization either directly by immediate contact of the gases with the material to be treated or indirectly through the medium of furnace walls and in providing means for the rapid coolin of the product and the utilization of the cat recovered therefrom in the process of such cooling. 7

These and other objects will appear from the following description of anapparatus illustrated. diagrammatically and by way of example in the annexed drawing, in which Figure 1 is a longitudinal section of a two-part furnace fitted with heat recuperating or economizin means, the dotted arrows in this figure in icating the course of the material undergoing treatment, the full line arrows indicating-the different courses followed by the gases of combustion, and the broken arrows indicating the course of the recovered gases.

Fig. 2 represents a plan view of the twopart furnace shown in the preceding-figure, partly broken away.

Figure 3 is a more or less diagrammatic View of clinker cooling apparatus adapted to be applied to the delivery end of the fur- Figure 7 is a detail longitudinal section of a modified form of furnace.

Figures 8 and 9 are respectively detail vertical and horizontal sections of the damper, and

Figure 10 is a longitudinal section of the means for cooling the clinkers combined with the furnace.

In Figure 1, a is the high tem erature furnace -or furnace section and is the low temperature furnace or section. The furnace at is fitted with a source of heat a such as the blow flame burner seen to the left hand of Figure 1 and it is also fitted overits whole length with a stron lining which is insulated as much as possi le from the external tube or casing. The, function of the furnace a is to roast or calcine the material received from the furnace b, which material arrives in the furnace a in a dried and granulated form at a relatively high temperature and reasonably free from powder.

detail longitudinal" section,

followed, in the form of a paste.

' fore proposed to withdraw such gases, or

some of them, atthis oint, and to recover fromihem the excess of heat which they contain. Owing to their dryness and the small amount of powder borne byv them, these gases are in the best possible condition for their treatment in the heat recovery apparatus'. This recovery of the excess heat and I regulation of the temperature in the low temperature furnace can be carried out in either one of two different ways. In the first, the gaseous stream is divided and one part is withdrawn and is directed into the apparatus for the extraction of its heat, the remaining part which passes into the furnace b being calculated so as to carry sufficient heat for the performance of the op: erations in the furnace b. In the second, the temperature of gases coming from a is lowered in the heat recovery apparatus and the gases are then admitted to the furnace 6. Thus, the whole of the stream of gases from a may be passed through the said apparatus for the extraction of their excess heat" and may then be admitted to the furnace b, at the lower temperature.

In practice, these two methods will 'gencrally be combined because neither the one nor the other alone permits of obtaining the best results in the furnace b. It is by the combination of the two methods that it is possible to regulate the temperatures, volumes and quantity of heat of these gases for the purpose of ensuring the greatest economy in their utilization. This is illustrated by Figure 1 in which, at the right hand end of the furnace a the escaping gases are divided into two parts, one part passing in a rapid ascending current up the refractory tube 23 and so into the furnace b, whilst the other part passes into the chamber (Z and soto the heat recovery apparatus. The first part of these gases is drawn up the tube 2' owing to the suction of the fan at t and it is through this tube that the material falls from the deliyery end of the furnace 6 into the entry end of the furnace a. The dust contained in the substance under treatment and from which it is cleared away by the hot gases themselves by their passage in the tube 71, is

gathered in the chamber 0, which constitutes the head of the furnace 6 and is disposed in owing to the suction of the fan at q and any dust or powder carried by this stream is deposited in the chamber d before passing to the heat recovery apparatus at e. The latter may be a steam boiler'or water heater, and after its passage through c, the current may be again divided into two parts the relative values of which may be varied byadjustment of the valves or dampers f and 9. That part which is under control of the valves f passes into a chamber j and from thence into the furnace b where it mixes with the very hot gases coming directly from the furnace a. The other part which is under control of the valves or dampers 9 passes through, say, feed water heaters r for the boilers at e and is delivered by the fan into the factory. v The heat still remainmg in these gases may be used for the drying of the raw material or of the coal, these gases being suitable for the purpose on account of their small content of oxygen and consequent inability to form an explosive mixture.

The hot gases coming directly from the furnace, a and passing up the tube 2' enter the surface I; by way of the annular space around the tube M which delivers the colder gases from the heat recovery apparatus. Thus the hot gases in this annular space will heat the material passing through the same which materials are then about to be transferred to the furnace a. The tube a is in rigid connection with the furnace b and revalves with it, the outer end of the tube u extending into and giving communication with the chamber j into which the gases from the heat recovery apparatus are delive;ed under control of the valves or dampers The valve or damper hconsists of a block of fire-proof material, which forms one wall of a rectangular funnel into which the substance'coming from the preparation furnace 5 falls and by which it is led into the refractory tube 2', through it falls into the calcination furnace a. In the tube 2', the substance is cleaned of dust by its fall through the current of ascending hot gas coming from the calcination furnace a, the volume of which current is regulated by the valve or damper h.

By advancing or retarding this valve or damper, the opening of the funnel is decreased or increased which results in an increase or decrease in the Volume of the gaseous current.

The lining of the furnace 6 towards its delivery end b may be of refractory material carefully insulated from the outer tube or casing whereas that portion 1) towards the inlet end for the raw material may have a metallic lining b as the falling temperature at this part permits of this and the metal lining takes up more of the heat of the gases which are about to escape from the furnace 6 than is taken up by a refractory lining. In fact, the difference in tempera ture between the lining and the gases is no longer of much importance so that it is of advantage to facilitate by any means the exchange of heat and to remove from the gases before they pass to the chimney the greatest quantity of heat possible.

The general arrangement hereinbefore described permits of easy regulation and control not only of each individual part of the installation but also of the whole plant including the heat recovery apparatus. If the dampers f and g be closed, all the gases from the furnace a will pass into the furnace b and the apparatus will function in a manner'similar to an ordinary rotary furnace. In this phase of control it is obviously necessary to moderate'the flame so that the disengagement of CO only commences after the entry of the material into the furnace a. The output and heat economy of the furnace are now reduced to that of an ordinary long furnace and the heat recovery apparatus is out of action. If the dampers g and h be fully opened, only a art of the gases from the furnace a is de ivered through the tube 11 into the furnace b and if this part is equal to about to of the whole volume, it may suffice for effecting the drying and heating of the raw material in the dry process in the furnace b. The heat in the remainder of the gases i be possible to pass 'the chamber and tube at will then be wholly taken up'in the'heat' recovery apparatus. tions are such as to make this mode of operation preferable, then it would be possible to considerably reduce the dimensions of and even to omit them altogether. Lastly, if the damper f be fully opened and the damper h be almost closed, practically all the gases will pass from the furnace at to the heat recovery apparatus and if the dampers a be closed all these gases will pass from the recovery apparatus to the furnace b By making the heat recovery apparatus sectional or compartmental, it is easily possible to regulate the amount of heat absorbed therein by opening more or less of the sections or comartments to the passage of the gases, or in other words, varying the heating surface. Generally speaking, this mode of working would suit best the so-called wet process, and -if the plant is to be more particularl adapted for working that process it would the gases from the chamber through the tube u directly into the head 0 of the furnace I), instead of extending the tube u well into the furnace b. In

If the working condisuch an apparatus,- the dimensions of the heaters 1' and fan 1 could be greatly reduced.

If there be further added to the regulating means above described, regulating means for varying the intensity of the blow flame and regulatingmeans for varying the speed of rotation of either or both of the furnaces a and b, it will be realized that there are extensive facilities for regulating and controlling the working of theplant for 0htaining all kinds of effects. Therefore it is now possible to arrange for the most economical conditions of working for each particular case as it arises.

-The' course of the material undergoing treatment in the installation is the same in all cases and is as represented in Figure 1, the said material being supplied to the entry end of the furnace b by a suitable feed or distributor. then passing through the furnace b and falling through the tube 11 into the furnace a and eventually leaving the delivery e'ndof the furnace a in the form of clinker. v

The cooler, Figures 3, and 4, is arranged as shown at m at the delivery end of the furnace at to receive the clinker and cool the same before delivery. It is very advantageous to cool the clinker with great rapidity and to recover from the same as much as possible of ,theheat, For this purpose, the cooler isadapted for forcing the cooling air to pass through the layer of clinker and owing to its efficient action may be very short in length. The cooler is composed of a number of elements, one of which is seen in detail in Figure 4, bolted in a circular series around the interior of a perforated cylindrical casing or drum. As will be seen, eacheleme nt comprises a casting Z presenting a cavity. the circumferential wall of this casting having a perforation s and the opposite wall being adapted, for the fixing therein. of a plate m. The elements are mounted in the casing or drum 'so that the plates an overlap one another but leaves slits or apertures between for the passageo'f air, and'so that the perforations sregister with appropriate perforations in the cylinder or drum.

As will be seen from Figure 3, and assuming the cooler to be rotating in the direction of the arrow, the clinker coming from the furnace a is distributed in a layer extending from the lowermost point in the interior for some little distance .up the cylindr cal nterior. The external air enters by'th perforations in the casing and throng 1 the perforations 3 into the cavities of the castings 1 so as to cool the latter over their whole length. The air then passes beneath the plates m and cools the latter and finally passes through the slits or apertures between the plates m and through the layer of clinker ments which for the time being are carrying clinker and not to the remaining elements, This result is achieved -by enc rcling the drum witlfastcel belt or band 0 which lat ter, at the place where the clinker-carrying elements are situated, is diverted from the periphery of the drum by means of pulleys p p and so on. By adjusting the distance apart of the pulleys p p the number of openings s uncovered for the admission of cooling air is varied and by displacingthe whole pulley arrangement around the periphery of the drum, the air admission zone 1s correspondingly shifted. It is therefore easy to regulate at will, the admission of coolingair and to force this air to pass through the layer of clinkers.

. It is to be noted that-the furnaces a and b are 'shown as havinga horizontal disposition in the drawing, but they willybe usually inclined for the travel of the material downwards from the entry'end to the delivery end. The inclination is usually very slight as, for example, five or six degrees from the horizontal.

From the foregoing, it will be seen that the process is divided into two principal parts namely, the high temperature parttaking place in the furnace a and the relatively low temperature part takingv place in the furnace b. However,it is apparent that the part of the process conducted inthe furnace b may be regarded as itself divided into two parts, the one being conducted in the-higher temperature zone of the furnace b which is lined with refractory walls and the other in the lower temperature zone of the furnace b which is provided with a metal lining for increasing the heat exchange capacity and recovering as muchas possible of the heat of .the gases prior to their departurefrom the furnace b, as clearly shown in Figure 5.

Obviously, therefore, it would be possible to.

divide the furnace 7) into two parts one having a refractory lining and the other having a metal lining, should that method of working be preferred.

I claim 1. Apparatus for roasting cement which includes a rotary furnace for low temperature treatment, a rotary furnace for high temperature treatment, a source of heat applied to the latter, feed means located at one end of the low temperature furnace, and delivery means located at the opposite end of the low temperature furnace; said apparatus comprising,'means disposed at the extremity i of the entrance of the high temperature furnace for moving the gases of combustion from one furnace to the other in a direction opposite thatfollowed by the substance under treatment, and means for dividing the current of gas issuing from the high temperature furnace whereby only a predetermined amount of the current is admitted to the low temperature furnace.

2. Apparatus for roasting cement which includes a rotary furnacefor low temperature treatment, a rotary furnace for high temperature treatment, a source of heat applied to the latter, feed means located at one end of the low temperature furnace, and delivery means located at the oppositelend of the low temperature furnace; said apparatus comprising, means disposed at the extremity of the entrance of the high temperature furnace for moving the gases of combustion in said furnaces in an-opposite direction to that follow'ed by the substance under treatment in said furnaces, means for.

predetermined amount of the current is admitted to the low temperature furnace directly, means for recovering the heat, and means for passing the remaining gases into the heat recovery means.

3. Apparatus for roasting cement which includes a rotary furnace for low temperature treatment, a rotary furnace for high temperature treatment, a source of heat applied to; the latter, feed means located at one endof the low temperature furnace, and delivery means located atthe opposite end of the low temperature furnace; said apparatus comprising, means disposed at the extremity of the entrance of the high temperature furnace for moving the gases of combustion in said furnaces in an opposite direction to that followed by the substance un der treatment in the furnaces, means for dividing the current of gas issuing from the high temperature furnace whereby only a predetermined amount of current is admitted directly to the low temperature furnace, meansfor recovering the heat and means for passing the remaining gases into the heat recovery means, a conduit connecting the head of the low temperature furnace to for roasting cement which.

' delivery means located at the opposite end of the low temperature furnace; said apparatus comprising, means disposed at the extremity of the entrance of the high temperature furnace for moving the gases of combustion in said furnaces in an oppo ite direction to that followed by the substa 106 under treatment in the furnaces, means for dividing the current of gas issuing from the high temperature furnace whereby only a predetermined amount ofcurrent is admitted directly to the low tem erature furnace, means for recovering t e heat and means for passing the remaining gases 1nto p the heat recovery means, a conduit connecting the head of vthe low temperature. furnace to the extremity of the entrance of the high temperature furnace, valve mechanism for regulating thefiow'of gases from the high temperature furnace to the low temperature furnace and then into the said heat recovery means, and valve mechanism for regulating the quantity of gas passing from the heat recovery means into the head of the low temperature furnace, said mechanism being mounted over the delivery tubes connecting the heat recovery means and the low temperature furnace.

5. Apparatus for roasting cement which includes a rotary furnace for low temperature treatment, a rotary furnace for high temperaturetreatment, a source of heat applied'to the latter, feed means located at one end of the low temperature furnace, and.

delivery means located at the opposite end of the low temperature furnace; said apparatus comprising, means disposed at the extremity of the entrance of the high temperature furnace for moving the gases of combustion in sald furnaces in an opposite direction to that followed by the substance under treatment inthe furnaces, means for dividing the current of gas issuing from the high temperature furnace whereby only a predetermined amount of current is admitted directl to the low temperature furnace, means for recovering the heat and means for passing the remaining gases into the heat recovery means, a conduit connecting the head of the low temperature furnace to the extremity of the entrance of the hightemperature furnace, valve mechanism for regulating the flow of gases from the high temperature furnace to the low temperature furnace and then into the said heat recovery means,

valve mechanism for regulating the quantity of gas passing from the heat recovery means into the head of the low temperature furnace, said mechanism being mounted above the delivery tubes connecting the heat recovery nfeans of the low temperature furnace said "paratus comprising, means disposed at the cture furnace and then into the heat recovery means and the low temperature furnace, said delivery tubes being centrally disposed at the extremity of the outlet of said furnace which is arranged to leave an annular space sufficient for the delivery of the substance as well as for the flow of that portion of the gas passing directly from the high temperature furnace to the low temperature furnace, and valve mechanism for regulating the proportion of the respective quantities of said directly passing gas and'of the gas passing through the heat recovery means.

6. Apparatus for roasting cement which includes a rotary furnace for low temperature treatment, a rotary furnace for high temperature treatment, a source of heat aplied to the latter, feed means located at one end of the low temperature furnace, and delivery means located at the opposite end extremity of the entrance of the high temperature furnace for moving the gases of combustion in said furnaces in an opposite direction to that followed by the substance under treatment in the furnaces, means for dividing the currentof gas issuing from the high temperature furnace whereby only a predetermined amount of current is admitted directly to the low temperature furnace, means for recovering. the heat "and means for passing the remaining gases into the heat'recov'ery means, a conduit connect ing the head of the low temperature furnace to the extremity of the entrance of the high temperature furnace, valve mechanism for regulating the flow of 'gasesfrom the high temperature furnace to the low, temperathe said heat recovery means, valv'e mechanism for regulating the quantity of gas passing from to thehead of the low temperature furnace, said mechanism being mounted above the delivery tubes con necting the heat recovery means and the low temperature furnace, said delivery tubes being centrally disposed at the extremity of the outlet of said furnace which is arranged to leave an annular space sufficient for the delivery of the substance as Well as for the flow of that portion of the gas passing directly from the high temperature furnace to the low temperature furnace, and valve mechanism for regulating the propor tion of the respective quantities of said directly passing gas and of the gas passing through the heat recovery means, andvalve mechanism for regulating the proportions of gas passing from the heat recovery means to the exhaust pipe andto the low temperature furnace respectively.

-7. Cement roasting apparatus comprising high and low temperature furnaces connected in series and adapted, to be successively traversed in opposite directions by the material to be treated and the gases of combustion, there being a connecting duct between the delivery end of the first furnace and the entering end of the second furnace,

a dust deposition chamber arranged at the' entering end of the second furnace and adapted to receive a portion of the gases therefrom, a heat exchange apparatus connected with said deposition chamber, means for drawing gases out of the second furnace and through said deposition chamber and said heat exchange apparatus, and means for delivering to the first furnace a pre-determined proportion of the gases cooled in the exchange-apparatus, substantially as set forth;

8. Cement roasting apparatus comprising a low temperature treatment furnace, a high temperature treatment furnace, feed means applied to one end of the low temperature furnace, a delivery head and duct applied to the opposite end of the low temperature furnace said duct projecting into the entering end of the high temperature furnace, means for drawing off, cooling and returning to the low temperature furnace a desired proportion of the gases issuing from the high temperature furnace, a metal lining to that end portion of the low temperature furnace which is adjacent to the feed, a refractory lining to the remaining portion of the low temperature furnace, and means for moving gases through said furnaces in opposition to the travel of material through the same, substantially as set forth.

9. In combinatioma low temperature rotary cement furnace, feed means at one end and a stationary head at the other end there of, a high temperature rotary furnace, a connecting duct between said stationary head and the entering end of the high temperature furnace, a source of heat for said high temperature furnace means for recovering the heat from a portion of the gases issuing from said high temperature furnace and a cooling drum adapted to receive the material delivered'from the exit end of the high temperature furnace, said drum comprising on its interior overlapping plates over which the material is distributed in a layer and air admission ports adapted for admittingair to pass between said plates and through the layer of material substantially as set forth.

10. e In combination, a low temperature rotary cement furnace, feed means at one end I and a stationary head at the other end thereof, a 'high temperature rotary furnace, a

connecting duct between .said stationary material, a travelling band encircling said drum for the greater part of its periphery and an assemblage of band diverting pulleys adapted for diverting said band from a portion of the periphery of said drum substantially as and for the purpose set forth.

11. In combination, a low temperature rotary cement furnace, feed means at one end and a stationary head at the other end there of, a high temperature rotary cement fur-' nace, a connecting duct between said stationary head and theenteringend of the high temperature furnace, a source of heat for said high temperature furnace, means for recovering a portion of the heat issuing from the said high temperature furnace, a cooling drum adapted for receivin material delivered from the exit end of the high ternperature furnace said drum comprising on its interior overlapping plates over which the material is distributed in a layer and air admission ports in its peripheral wall for admitting air to pass between said plates and through said layer, a travelling band encircling said drum for the greater portion of its periphery, an assemblage of band diverting pulleys adapted. for diverting said band from a portion of the periphery of said drum, and means operative on said assemblage for the bodily adjustment of said assemblage around said drum as well as for the adjustment of the extent of the arc of the drum uncovered owing to the action of the diverting pulleys substantially as and for the purpose set forth.

Iutestimony, that I claim the foregoing as my invention, I have signed my name this 

